[4][5] He is one of the seven most revered rishis (the Saptarishi) in the Vedic texts,[6] and is revered as one of the Tamil Siddhar in the Shaivism tradition, who invented an early grammar of the Old Tamil language, Agattiyam, playing a pioneering role in the development of Tampraparniyan medicine and spirituality at Saiva centres in proto-era Sri Lanka and South India.

[13] The fourth theory, based on folk etymology in verse 2.11 of the Ramayana states that Agastya is from aga (unmoving or mountain) and gam (move), and together these roots connote "one who is mover-of-mountains", or "mover-of-the-unmoving".

[21][22][23] According to inconsistent legends in the Puranic and the epics, the ascetic sage Agastya proposed to Lopamudra, a princess born in the kingdom of Vidarbha.

However, the legends state that Lopamudra accepted him as her husband, saying that Agastya has the wealth of ascetic living, her own youth will fade with seasons, and it is his virtue that makes him the right person.

Two legends place it in Northwest Maharashtra, on the banks of the river Godavari, near Nashik in small towns named Agastyapuri and Akole.

In Southern sources and the North Indian Devi-Bhagavata Purana, his ashram is based in Tamil Nadu, variously placed in Tirunelveli, the Pothigai Hills, or Thanjavur.

[2][17] He ran a Vedic school (gurukul), as evidenced by hymn 1.179 of the Rigveda which credits its author to be his wife Lopamudra and his students.

The hymns composed by Agastya are known for verbal play and similes, puzzles and puns, and striking imagery embedded within his spiritual message.

[31] However, some scholars interpret the same hymns to be an allegory for any two conflicting ideologies or lifestyles, because Agastya never uses the words Arya or Dasa, and only uses the phrase ubhau varnav (literally, "both colors").

[22][32][33] The theme and idea of "mutual understanding" as a means for lasting reconciliation, along with Agastya's name, reappears in section 1.2.2 of the Aitareya Aranyaka of Hinduism.

[34] The second theme, famous in the literature of Hinduism, is a discussion between his wife Lopamudra and him about the human tension between the monastic solitary pursuit of spirituality, versus the responsibility of a householder's life and raising a family.

[14] Sage Agastya is mentioned in the Hindu epic Ramayana in several chapters with his hermitage described to be on the banks of river Godavari.

He is described by Rama as the sage who asked Vindhya mountains to lower themselves so that Sun, Moon and living beings could easily pass over it.

He is also described as the sage who used his Dharma powers to kill demons Vatapi and Ilwala after they had jointly misled and destroyed 9,000 men.

[5] Agastya, according to the Ramayana, is a unique sage, who is short and heavy in build, but by living in the south he balances the powers of Shiva and the weight of Kailasha and Mount Meru.

[18] Agastya, once again, stops the Vindhya mountains from growing and lowers them and he kills the demons Vatapi and Ilvala much the same mythical way as in the Ramayana.

The Tamil text Purananuru, dated to about the start of the common era, or possibly about 2nd century CE, in verse 201 mentions Agastya along with many people migrating south.

[50][51] The northern traditional stories, states Mahadevan, are "nothing more than a collection of incredible fables and myths", while the southern versions "ring much truer and appear to be a down to earth account of a historical event".

Sivaraja Pillai, for example, there is nothing in the early Sangam literature or any Tamil texts prior to about the mid 1st millennium CE that mentions Agastya.

[52][53] The earliest mention of the role of Agastya in Tamil language, according to Richard Weiss, can be traced to the Iraiyanar Akapporul by 8th-century Nakkirar.

He is described as the one who perfected and loved both Sanskrit and Tamil languages, amassing knowledge in both, thus becoming a symbol of integration, harmony and learning, instead of being opposed to either.

This Tamil concept has parallels to Tibetan mahasiddhas, Sri Lankan Buddhist, and Nath Hindu yogi traditions of north India.

[65] The Agastya-Jataka story is carved as a relief in the Borobudur, the world's largest early medieval era Mahayana Buddhist temple.

He introduced the Vedic science and the Pallavan Grantha script, but his popularity declined when Islam started to spread throughout the islands of Indonesia.

The chapters of the Javanese text include the Indian theory of cyclic existence, rebirth and samsara, creation of the world by the churning of the ocean (samudra manthan), theories of the Samkhya and the Vedanta school of Hindu philosophy, major sections on god Shiva and Shaivism, some discussion of Tantra, a manual-like summary of ceremonies associated with the rites of passage and others.

[72][73] In Cambodia, the 9th-century king Indravarman, who is remembered for sponsoring the building of a large number of historic temples and related artworks, is declared in the texts of this period to be a descendant of sage Agastya.

Scholars such as Moriz Winternitz state that the authenticity of the surviving version of this document is doubtful because Shaiva celebrities such as Skanda and Agastya teach Vaishnavism ideas and the bhakti (devotional worship) of Rama, mixed in with a tourist guide about Shiva temples in Varanasi and other parts of India.

[77][78] Agastya is attributed to be the author of Agastimata, a pre–10th-century treatise about gems and diamonds, with chapters on the origins, qualities, testing and making jewellery from them.

For example, Agastya is featured inside or outside of the temple walls and sometimes as a guardian at the entrance (dvarapala), with or without a potbelly, with or without a receding hairline, with or without a dagger and sword.

[87] The shrine to Agastya at the Pothigai hill source of the river is mentioned in both Ilango Adigal's Silappatikaram and Chithalai Chathanar's Manimekhalai epics.